Pilot nozzles are used in gas turbine engines to ignite a fuel/air mixture. In particular, the pilot nozzle ignites a mixture of liquid fuel and/or gas fuel with air in a combustion zone located downstream from the pilot nozzle. Additional fuel nozzles, including main fuel nozzles, are also provided to combust further portions of a fuel/air mixture. The fuel and the air are typically mixed together in a swirling zone and are ignited in the combustion zone to create a high-energy fluid flow to produce a hot working gas which is conveyed to a turbine section to extract a work output for the gas turbine engine.
Stringent emissions requirements in the US. and abroad have required design improvements to the combustor section of the gas turbine engines, including provision of Ultra-Low NOx (ULN) combustor designs to operate with low NOx emissions, as well as lower CO, VOC and particulate emissions Such ULN designs can include dual fuel ULN pilot nozzles that facilitate control of the combustion process during various operating conditions to minimize emissions